We report preliminary results from a multiwavelength campaign aimed at the flaring activity of Sgr A*, which was carried out in early April 2009. Simultaneous data were collected in X-ray, near-infrared, and submillimeter wavebands with the XMM-Newton satellite, the VLT, and the APEX telescope, respectively. We present the detection of several flares and briefly discuss their properties in the context of the synchrotron self-Compton and plasmoid expansion models.